gradient clipping mask not working in PSE 15

I am trying to blend using a gradient, but when I clip photo to gradient nothing happens. I'm sure I'm missing something obvious as I have done this procedure many times. Feeling real stupid, but not to ashamed to ask

Ahh. Thank you! I knew it was something simple that I was missing. I wanted to use the gradient to gradually blend the photo into the paper. A standard technique I use quite often, but could not figure out why it wasn't working this time. I appreciate your taking the time to help.